Re: New primitive types?

> On Tue, Aug 1, 2017 at 8:08 PM Carter Schonwald <[hidden email]>
> wrote:
>> One issue with packed fields is that on many architectures you can't
> quite do subword reads or
>> writes. So it might not always be a win.
>
> Could you give any examples?

Historic DEC Alpha, now long obsolete.

It is very hard to create compliant and performant implementations of
Java 5, C 11 or C++ 11 on such architectures. All these languages
(and their subsequent revisions) require that naturally aligned
objects can be accessed independently. For example, you can't use a
simple read-modify-write cycle to implement a single-byte store using
word operations.

> On Tue, Aug 1, 2017 at 8:08 PM Carter Schonwald <[hidden email]>
> wrote:
>> One issue with packed fields is that on many architectures you can't
> quite do subword reads or
>> writes. So it might not always be a win.
>
> Could you give any examples?

Historic DEC Alpha, now long obsolete.

It is very hard to create compliant and performant implementations of
Java 5, C 11 or C++ 11 on such architectures. All these languages
(and their subsequent revisions) require that naturally aligned
objects can be accessed independently. For example, you can't use a
simple read-modify-write cycle to implement a single-byte store using
word operations.

That's why such architectures really do not have a future (or even a
present), except maybe in niche markets such as GPGPU (but even there,
things are heading towards the de-facto standard memory model).

> * Michal Terepeta:>> > On Tue, Aug 1, 2017 at 8:08 PM Carter Schonwald <> [hidden email]>> > wrote:> >> One issue with packed fields is that on many architectures you can't> > quite do subword reads or> >> writes. So it might not always be a win.> >> > Could you give any examples?>> Historic DEC Alpha, now long obsolete.>> It is very hard to create compliant and performant implementations of> Java 5, C 11 or C++ 11 on such architectures. All these languages> (and their subsequent revisions) require that naturally aligned> objects can be accessed independently. For example, you can't use a> simple read-modify-write cycle to implement a single-byte store using> word operations.>> That's why such architectures really do not have a future (or even a> present), except maybe in niche markets such as GPGPU (but even there,> things are heading towards the de-facto standard memory model).>